"I felt comfortable with the car," Rosberg said. "It is quite challenging - the car snaps quite suddenly, but I got a good lap together."

Mercedes have now locked out the front row on 12 occasions this season

Hamilton said: "It was lots of fun out there for all of us. It's a shame we couldn't go out at the end.

"I had hoped we could go out and clean the track. It looks like a lot of people have turned up today to watch. I hope the weather eases up for the race."

Ricciardo said he expected "we will have a lot of run" in the race.

The race is due to start at 14:00 local time (19:00 GMT) and weather forecasts suggest conditions will improve by then.

Title permutations: Can Hamilton win in Austin?

If Hamilton wins, Vettel must finish second to prevent Hamilton winning the title at the US GP

If Hamilton finishes second, Vettel must finish fifth or Nico Rosberg must win the race to prevent Hamilton winning the title

If Hamilton finishes third, Vettel must finish sixth or Rosberg must finish second

If Hamilton finishes fourth, Vettel must finish eighth or Rosberg must finish third

If Hamilton finishes fifth, Vettel must finish ninth or Rosberg must finish fourth

If Hamilton finishes sixth, the title battle will continue to the next race in Mexico, even if Vettel does not finish or collects no points. Rosberg would need to come fifth to still be in contention.

Austin, Texas, is still being affected by rain on the periphery of tropical storm Patricia and has seen record amount of rain in the last 24 hours.

Behind Alonso will be Williams's Valtteri Bottas, Lotus's Romain Grosjean and the second McLaren of Jenson Button.

Alonso has a new-specification Honda engine in his car, which was not available to Button this weekend, prompting the Englishman to joke on Thursday that he hoped his team-mate would "annihilate" him.

Unfortunately for him, he got his wish, at least in qualifying - Button was 0.928secs slower than Alonso, significantly more than the small improvement in power in the upgraded engine was worth in lap time.

Media playback is not supported on this device

Re-born in the USA - F1 in America

Button, who was complaining about a lack of rear grip, said conditions at the end of the second part of the session were too dangerous.

"At the end," he said, "the team were like, 'Come on, one last big push.' And I was like, 'Right'. I was just floating."

Vettel added that the weather had meant the track was in "red flag conditions".

A number of drivers had spins during the treacherous session, with the fast kink at Turn 10 proving the most dangerous part of the track - Hamilton, Vettel, Hulkenberg and Raikkonen were among the drivers who lost control there.

Media playback is not supported on this device

Further rain expected for race day at the Grand Prix in Texas

But despite the difficult conditions only one driver crashed - Toro Rosso's Carlos Sainz lost control at Turn Four and smashed into the wall on his second flying lap in the first part of qualifying.